The present invention relates in general to pressure sensors and, more particularly, to an electronic absolute pressure sensor.
Electronic pressure sensors are commonly used to convert gaseous or liquid pressure to an electrical signal representative of that pressure. Typical applications include intake manifold pressure sensing for automotive engines, dual braking system pressure sensing, air conditioning high/low pressure line sensing, pressure regulation of compressed gases in industrial environments, and altimeter/cabin pressure sensing and regulation for aerospace applications.
The pressure sensor measures external pressure against some reference pressure. Gauge-type pressure sensors measure pressure against an external dynamic reference and provide a difference reading. Absolute-type pressure sensors compare the external pressure to be measured against a static internal reference to provide the difference reading. The absolute pressure reference is typically a very low pressure, or near vacuum, say 20 millitorr. The low pressure reference allows comparisons to be made accurately from above standard barometric pressures to nearly vacuum.
Pressure sensors typically include a sensor die having a piezoelectric network mounted on a silicon diaphragm that flexes in response to the differential pressure. The sensor die converts the degree of flexing to an electrical signal. In the prior art, one sensor die is mounted in one plastic package. Unfortunately, the sensor package tends to be quite large in comparison to the sensor semiconductor die that performs the actual pressure sensing function. Moreover, the sensor packaging accounts for a large percentage of total manufacturing costs.
Hence, a need exists to make the most efficient use pressure sensor packaging with respect to the pressure sensing function.